Thermostatic control of a vent in a chamber



March 12,"1929. Hi. M. @ONE 1,705,176

lTHERMOSTATIG CONTROL OF A VENT IN A CHAMBER Filed April 19. 192s 2 Sheetssheet. l

March l2. 1929. H. M. come:` 1,705,176

THERHOSTTIC CONTROL OF' A VENT IN A CHAIBER` Fl d A l e pnl 19' 1926 2 sheets-sheen 2 /awar/ (one @Patented Mar; 12, 192e.

UNITED STATES 1,705,176 PATENT OFFICE.

HOWARD M. GONE, OF LONGVIEW, XVASHINGTON, ASSIGNOR OF ONE-HALF T THE LONG-BELL LUMBER COMPANY, OF KANSAS CITY, MISSOURI, A. CORPORATION OF MISSOURI.

THERMOSTATIC CONTROL OF A VENT IN A CHAMBER.

Application inea April 19, 192s.

My invention relates particularly to the control of the relative humidity in lumber dry kilns by thermostatically operated means, although the same may be profitably employed for other uses. I will confine the description of my invention, however, to its use in a lumber kiln in this connection.

It is convenient to quote the following from Bulletin A (October 1925 edition) entitled Tycos Instruments for Lumber Dry Kilns published by the Taylor Instrument Companies, of Rochester, New York.

It is Well known that two of the most important factors in lumber drying-are temperature and humidity. One of the advantages of kiln drying is, that it is possible t'o maintain proper drying conditions independent of weather conditions, thereby controlling,r the drying process and the final moisture content. s am Even the most inetliciently operated kiln is capable of evaporating moisture from wood. The. real problem, however, 1s to remove the moisture in the shortest time. possible, without impairing the quality of the stock being dried, and with the minimum of steam consumption and kiln supervision.

The amount of moisture in the air affects the rate at which the moisture is evaporated from the surface of the stock, and the extent to which the wood Will dry. If the air is very dry (humidity too low) excessive evaporation causes the libres to` become, stiff and dry, resulting in extremecase hardening. This condition causes unequal stresses in the boards, which if allowed to'continue, results in familiar defects, such as checking, warping and in loss of time and expensive kiln operations.

To maintain proper drying conditions, by hand adjustment of spray and heat-line valves is practically impossible. Therefore, automatic devices for controlling `the spray and heat-line valves were heretofore provided as described insaid bulletin.

But ythe mere automatic control of the spray and heat lines is not sufficient. The dead steam and air which collects under the roof of the dry kiln and does not circulate causes inequalities in the temperatures in the kiln. Not only this, the latent heat given off by the condensat-ion of the moisture in the lumber, 'after the spray-line is turned off, tends to cause sudden rises in the temperature,

Serial No. 103,048.

and thus a sudden fall in humidity will re.- sult. A sudden increase in heat and correspondmg,r fall in. humidity will dry the lumberl too quickly; and the last mentioned condltions cannot'be anticipated nor prevented except bythe opening of the covers of the vents in the roof of the kiln to permit the escape of the dead steam and heat.

At the present time the covers'of the vents in the roof of the kiln are manually operated by an attendant who may, or may not always, be on duty. In any event no matter how careful he is, he has'no accurate means of knowing exactly' how much', when or how long to open or keep open these covers. But regardless of the operators experience, and the skill which'he may acquire, it is not within human ability instant-ly to change the position of the roof covers, so that the proper temperature and humidity will always c malntained. The change in temperature and humidity has occurred before the eye can detect it, or the hand prevent it.

The object of my invention is to provide an eflicient automatic control for the roof vents in dry kilns; thus to relieve the operator of the constant necessity of constant watching and assuring that the roof vents will be controlled so as to co-operate with the' heatingr coils and the spray-line to assure just the right predetermined temperature and humidity.

I attain-my object by providing automatic thermostatic controlled means for opening and closing the spray line valve and the roof vents in time with each other. This control, is effected through the medium of a wet bulb or dry bulb similar to the operation of said 'lyeos device, and located at any convenient. point within the kiln, and by providing means i'or imposing a variable predetermined interval of time between the operations of the spray line valve and roof vent control, in that way assuring an accurate cooperation of all the means provided vfor placing,r the air within the kiln in the predetermined desired state as to temperature and humidity, with regard to a run of a particular kind of lumber.

The automatic operation of the means for controllilugr the roof vents may be accomplished thru the medium of pressure operating devices, or thru the medium of electromagnetically operated devices, which in turn are automatically controlled by the thermostatic conditions within the kiln. Both of these means are illustrated in the accompanyingv drawings, and hereinafter fully dcscribed.

In 'the accompanying drawings, Fig. 1 shows a section of the roof of a kiln provided with a vent and means for controlling the outlet from the kiln through said vent, and illustrates diagrammatically one combination of devices by which the Vent-controlling means are thermostatically operated in order to attain the above mentioned objects and results. The devices here shown for operating the Vent controlling means are actuated by fluid pressure, and the thermostatie element provided for operating the vent-controlling. l vmeans'eonsistsof devices atpresent employed for controlling the temperature and humidity of a kiln chamber.

Fig. 2 shows a fragmentary perspective View of a section ofthe roorof a kiln provided l with a number ofvents, and the means for and cover thereof shown in Fig. 1 in order to any desired degree.

illustrate more clearly the arrangement of the cover by which it is adjustable for varying the control of the vent outlet.

. Fig. 5 illustrates diagrammatically that the thermostatically actuated means for controlling the roof vent may be varied; as for example, instead of using pressure actuating means, electro-.magnetically operating means may be used. Y

Upon-the roof a of the kiln I) are mounted, in alinement a number of`spaccd vents c controlled by dampers or covers d. These covers hang from rods e pivotally supported from the ends of arms f, rigidly secured to a rockshaft g. This shaft is suitably journaled in bearings h mounted to the roof a.

Prior to my invention the rock-shaft was rotated manually by means of an arm g set at any desired position'by a rack g2, as illustrated by Fig. 2, thereby opening the vents to Referring first to Fig. 1 The roof a of the dry kiln has a vent c controlled by a cover (l. The lpressure actuated device raises the diaphragin-lever k to which the stem of the pressure actuated device is suitably fastened. The lever c is fixed to rock-shaft g, which is 'jburnaled on the roof of the kiln in bearings h as mentioned, and actuates the cover-lever f from which is suspendedthe cover d.

The covercas shown in Figs. 1 and 4 comprises a cover 3()l rigidly suspended from the stem e, which sets tightlyover thevent c. A

sleeve 31 is formed on the underside of the cover 30 which fits loosely in the vent c providing a' space 82 between the sleevel and the side of the vent c to provide an opening on the cover, which is only slightly lifted. 'l'his sleeve 31 is provided with a nun'iber of triangular notches-33, so that as the cover is lifted the opening will gradually increase until the vent is opened to its fullest extent..

The arm tis weighted by a movable weight iwi?, thereby forcing the pressure actuated device to operate against said weight, and in that way providing means for regulating the amount ot' pressure required to lift the cover off the vent for more or less opening the latter.

It is assumed that the kiln is provided with a thermostatic control of the Tycos type, the actuating element, thus the wet-bulb for example, being located at any convenient -point in the kiln chamber.

The 'lycos device, as well known comprises a Bourdon typeof helical spring p, actuated by the wet-bulb thermometer m, and this spring expands or contracts as the humidity in the kiln rises or falls. The movement of tue helical springis tranmitted by arm g to penarm fr, recording all movements. on record-sheet t, which is rotated by a clock (not shown). The'pen arm is counter-balanced by weight fr and is pivotally'supported at s.

The movement of pen-arm r-is transmitted to pin-valvearm 'v by a horizontal link u. Said pin-valve-arm o is pivotally fixed at o anda actu'ates pin 2 of the needle valve by means of the set-screw 02, which holds the said pin 2 in place against the' fluid pressure in the valve chamber 3.

The direct set control, by which the desired humidity is is an adjusting nut z, connected by arm e. to the arm y which sets the pointer :l: for the desired thermostatic conA ditions in the kiln chamber. Ou. the arm 1/ is a slot y in which a stud y2 xed on the arm l 2 will he actuated. In the'side of the needle; valve 3 an air-.leak is provided as an escape for pressure in pipes 9 and 13, the air-leak being controlled by a set screw 4 as usual.

As the humidity in the kiln rises above a predetermined point the arm v'influenced by the wet-bulb thermometer m, opens the needle .valve 3 land allows the pressure to How from air reservoir 6 through supply pipe 5, into chamber 4 of the needle valve. The pressure then flows through pipes 9 and 13 to the pressure actuated means z' and 10, the latter controlling the spray line valve 11 as usual.

The weight wzf, suspended from the ar-m k.

is provided, so as to impose greater' resistance to the operationof the pressure actuated device z', in controlling the roof vent, than is imposed upon the pressure actuated device 10, by which the spray line valve l1 is operated; in that way causing the root vent/to be closed prior to the opening of the sprayeline valve, and vice versa, causingl the closing of the spray-line valve before the opening of the root vent. The weight wt is adjustable in order to vary the amount of resistance, imposed on the pressure actuated device z'.

The devices illustrated by Fig. l operate as follows:

When the humidity rises in the kiln chamber, the Bourdon springr of the wet bulb thermometer will be actuated, moving,r the pen-arm, recording?r such change, and simultaneously opening the needle-valve 2, and causing the pressure actuated device l() to be operated to shut ofil the steam-spray. Then if the humidity continues to rise. the pressure actuated device controlling the roof vent will be operated; the timing ot' the vent opening after the closing of the spray-valve is accomplished by adjusting the weight wt as mentioned.

A too sudden opening.,r ot the vents niustnot be permitted for such would canse the fluctuation' of the temperature and humidity and produce case hardening and checkingr in the lumber.

In order to prevent this it is necessary t0 gradually open the vents and it is preferable to arrange the vent opening and closing,r means so as to operate these means at a predeter mined accelerating rate. To this end as thc wet-bulb temperature rises, the cover 30 is first littcd from off the `vent thus permitting only a small amount of air to escape through the. space 32 between the sleeve 3l and the vent c. which if not sufiicient to relieve the excess` wet bulb temperature so that the wet bulb thermometer will either cease rising or fall as the case may be, the pressure operating devices will continue to lift the cover arm until the V-shaped notches 33 are raised above the rim of the vent c, thereby permittingr` a more rapid and accelerating rate of escape of the excess humidity until the wet bulb temperature falls and causes the cover arm to move downward and gradually' closes the said vent again. Likewise, if after a short time the smaller opening ot the vent should not be suthcient, the wet-bulb temperature will continue to rise and will cause tinally the larger cover-plate to be lifted off the vent.

Referring to Fig. 3 showing another type of vent control which comprises two parts d and d, the part d is fixed on the stern e by a set screw e and covers a hole in the larger cover d, which restson the vent. The larger cover d moves freely on the stern e. On the lower end of said stein is a spider d, which as the arm f rises, bears against and lifts the cover part d. Thus as the lever f rises the hole in the cover d is first opened, giving a partial outlet for the vent b, and finally the atter is opened to tull extent. Set in kthc cover rl are a number of adjusting screws n extendingr through and threaded into the spider (I2. so that the time the cover d will open before the cover is opened, may be controlled. This construction is especiall)v adapted to prevent, the too rapid opening otl the cover and to permit the control device to maintain a constant wct bulb temperature. within the kiln as when the smaller cover fl is first opened and if they excess humidity ia not sufficiently relieved, the pressure operating,r device will contimnl to lift the cover arm until the spider st rikes the larger cover plate (l. 'hen this occurs tht` weight of they larger cover-plate will be imposed upon the cove." arm f, and hence greater pressure will be rcquired to lift the latter. which tends to resist the greater opening of the vent. Thtl smaller opening of thc veut may be sufficient to relieve the excess wet bulb temperature; but if not the )ressure will build up and finally will lift ille cover-arm further. thereby lifting the larger cover-plate oli the vent and opening the latter wide.

Referring now to Fig. 5, the means here shown for operating the vent control are similar to those shown in Fig. l. except l'or the substitution of the electro-magnetic means as actuating power instead oll luid pressure. The root a; vent c, and covcrsv/ and d', are the same as shown in Fig. l. A\ solenoid sd when energized raises the solenoid lever k to which is afiixed the rock-shaft '(1, which actllates the co\\'er-levcl from which 'is suspended the cover controlling ;f vent c.

The solenoid ad is actuated by the variable Contact 20, which regulates the said solenoid so that it adually raises the solenoid arm and there' y the covers l] and Il in succession as before mentioned.

The plunger-arm 2l controls the variable. contact 20, and as the wet-bulb thernunneter m actuates the plunger arm 21. according to the degree of humidity in the kiln chamber. the variable Contact 20 controls the amount of current going to the solenoid SJ. As is apparent when the solenoid is (le-energized, the vent covefs will then be allowed to close down on said vents.

The thermostatic control which l provide for the roof vents of a kiln. as above described, may in like manner be applied to operate cold Vair gates located at the bottom of the kiln, or

lill) ilo tained as desired. It also reduces the amount of steam consumed in the spray, by automatically closing the roof-vent and inducing the evaporation of the moisture from the lumber, thereby utilizing the evaporated moisture as the medium for maintaining the desired humidity within the kiln.

While I have specifically mentioned the Tycos instrument in the foregoing description of my invention, it is, of course, to be understood that any other thermostatically actuated instrument may be used for operating the vent controlling and the air-conditioning meansthat is the air humidit'ying means, or the air heating means, or. both meansof the kiln chamber. Likewise, while I have described my invention as particularly applicable to a kiln chamber for drying lumber, it may also be found practical for ilse in drying other articles.

I claim:

1. The combination with a chamber provided with a vent, ot'automatic means tor controlling said vent, pressure actuated means for operating the vent-controlling means, a spray-line within the chamber, a valve in said spray-line, pressure actuated means foroperating the spray-line valve, an air-line connected to each ot' said pressure actuated means,a thermostatically controlled valve in said air-line, the actuating element of such tliermostatic control being located within said chamber, and means for differentiating the pressure required for operating the spray-line valve from that required t'or operating said vent-controlling means', whereby to cause the operation ot the latter means relatively to the operation of the spray-line-valve.

2. The combination with a chamber provided with a vent and afcover for said vent, otI automatic means for moving the cover off and on said vent, pressure actuated means for operating the cover-,moving means, a lspray-line within thechamber, a valve in said spray-line, pressure actuated means for operatingr the spray-line valve, an air line connected to each of said pressure-actuated means, a thermostatically controlled valve in said air-line, the actuating element ot' suoli thermostatic control being located within said chamber, an adjustable weight arranged to impose more or less resistance to the lifting of said vent-cover, whereby to cause the opening of the vent to follow the closing of the spray-line and to close the vent prior to the opening of the spray-line.

3. In a kiln, and the like, in combination, a' vent in the kiln chamber, a control for the vent, means for conditioning the air within the kiln chamber, a control for said air-conditioning means, means operated by a thermostatic instrument located Within the kiln chamber whereby said controls are operated, and adjustable means for imposing a prede-t termined interval of time between the o erating of the air-conditioning means and t e vent control j 4. In a kiln, and the like, in combination, a vent in the kiln chamber, a control for the vent, a spray line within the kiln chamber, a control for said spray line, means operated by a thcrmostatic instrument located within the kiln chamber whereby said controls are operated, adjustable means for imposing a predetermined interval of time between the operating of the spray line control and the vent control.

5. ln'a kiln, and the like, in combination, a vent in the kiln chamber, a cover for the vent and means for operating the same, means for conditioning the air within the kiln chamber, a control for said air-conditioning means, means operated by a thermostatic instrument located within the kiln chamber whereby said cover-operating means and said control are operated, and adjustable means for imposing a predetermined interval ot' time between the operating ofthe air-condit ioning means and the means for operating the vent cover.

6. ln a kiln and the like, in combination with a vent in the kiln chamber,` a. c'over t'or the vent, means for operating said cover, means for conditioning the air within the kiln chamber, a control for said air conditioning means, means operated by a. thermostatic instrument located within the kiln chamber whereby said cover and control are operated, and adjustable means for imposing a predetermined interval of time between the operatingr otl the air conditioning' means andthe vent cover, said cover operating means opening or closing the vent opening at a rate varying as compared with the corresponding movements ot' the cover.

7. In a kiln and the like, in combination with a vent in the kiln'chamber, a cover t'or the vent, means t'or operating the same, means for conditioningr the air within the kiln chamber, a control for said air conditioning means, means operated by a thermostatic instrument located within the kiln chamber whereby said cover operating means and said control are operated, and adjustable means for imposing a selective predetermined interval of time between the operating of the air conditioning means and the means for operating the vent cover, the cove r operating means opening and closing the vent opening at a materially increased rate as compared with the similar movements of the cover. L

HOWARD M. GONE. 

